Expansible and retractable packing structure



Jan. 19, 1960 E. H. CLARK, JR 2,921,632

EXPANSIBLE AND RETRACTABLE PACKING STRUCTURE Filed March 5, 1956 z len/zs 7195 C2 9/66, @Z.

IN VEN TOR.

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United States Patent EXPANSIBLE AND RETRACTABLE PACKING STRUCTURE The present invention relates to packing structures, and more particularly to packing structures adapted to effect a seal against the wall of well casings, well liners, and other confining enclosures.

Well packers are run in a well bore to a desired location or locations at which the packer is to be sealed off against a well casing, or similar conduit, disposed in the well bore. The packer usually includes a non-metallic packing member which packs off against the well casing, the packing member being prevented from moving longitudinally by an abutment portion of the packer tool. This abutment portion has substantial clearance with the wall of the well casing, to enable the well packer to be moved longitudinally in the well casing free from interference by the abutment portion. In view of the substantial clearance required, a relatively wide annular space exists between the abutment portion and the casing into which the non-metallic packing member tends to flow or to be extruded when subjected to high pressures or high temperatures, or combinations of the two conditions. Under some situations a substantial portion of the packing material may be dissipated through the clearance space, causing failure of the packing member. If the nonmetallic packing is of the expansible and retractable type, the forcing of substantial packing material into the aforenoted clearance space, when the packing member is in expanded condition, can result in subsequent inability to retract the packing member.

An object of the present invention is to provide an improved well packer, in which the non-metallic packing member is prevented from being forced into the annular clearance space around the adjacent abutment portion of the apparatus.

Another object of the invention is to provide a well packer embodying an expansible and retractable device for bridging the clearance space between the abutment portion and the casing wall when subjected to a substantial force, to prevent cold flow of the packing material, the bridging device beingnormally in retracted position and tending to return to such retracted position when the force urging the packing material toward the clearance space is relieved.

A further object of the invention is to provide a well packer' of the type indicated, in which no gap through the expansible and retractable bridging device exists when the device is in expanded condition, thereby providing no space through which the packing material can be ex- '.This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which'it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best definedby the appended claims.

2,921,632 Patented Jan. 19, 1960 Referring to the drawings:

Figure 1 is a combined side elevational and longitudinal section through an embodiment of the invention, with the packing structure in retracted position; s

Fig. 2 is a view similar to Fig. 1, with the packing structure in its expanded condition.

The apparatus is disclosed in the drawings as being applied to a well packer A of the retrievable type, which is adapted to be run in a well casing B, sealed off there within, and then released from the casing to be shifted to a different location therewithin, or to be withdrawn completely from the well casing. The invention will be described herein, by wayof example only, in connection with the specific well packer of the kind disclosed in the application of Martin B. Conrad, Serial No. 536,415, filed September 26, 1955, for Retrievable Double Holding Subsurface Well Tool, Patent No. 2,802,534. Itis to be understood, however, that the invention is applicable to other specific types of well tools, and to packing structures generally.

As illustrated specifically in the above identified patent application, a tubular packer body 10 is provided, which is suitably connected to a tubular string (not shown), such as drill pipe or tubing, extending to the top of the well casing B in which the apparatus is movable longitudinally, and in which it is used. This body 10 is adapted to be releasably anchored to the well casing, as by providing a plurality of circumferentially spaced slips 11 around the body having wickers or teeth 12 engageable with the wall of the well casing. The slips are urged outwardly into engagement with the wellcasingby a tapered or frusto-conical expander 13 slidably mounted on the body of the tool, which has a taperedexpander surface 14 adapted to coact with companion inner tapered surfaces 15 on the slips. Relative upward movement of the expander 13 Within the slips 11 shifts the latter outwardly into anchoring engagement with the Wall of the well casing B, after which a normally retracted packing structure 16" is expanded outwardly into sealing engagementwith thewall of the wall casing. I

The packing structure 16 includes a compression or booster sleeve 17 slidably mounted on the body of the tool, and threadedly secured to the lower portion of the expander 131 This expander 13 actually forms an upper abutment for the packing structure in conjunction with a fixed gage ring 18 threaded on the exterior of the lower portion of the expander. The gage ring 18 has an external diameter substantially less than the internal diam eter of the casing, there being a substantial annular clearance space 19 therebetween. Disposed around the compression sleeve 17 is an inherently contractible packing sleeve 20, which may be made of rubber'or rubber-like material. The upper end 21 of the packingsleeve is disposed within a generally cup-shaped expander'mem-- ber '22, which is slidably mounted on the exterior of the compression sleeve, this expander member having a downwardly and outwardly tapering portion 23 providing a pocket 24 with the compression sleeve receiving the upper end 21 of the rubber or rubber-like packing sleeve.

surface 27 companion to the externally tapered surface 25 on the expander member.

The expansible and contractable gage ring 26 normally occupies a retracted position, in which its peripheral poraaanesa" tion extends outwardly no further than the periphery of the fixed gage ring 18. However, the expansible gage ring can be shifted outwardly into contact withthe wall of the well casing to bridge the annular clearance space 19. between the abutment portion 18, that itcontin'ues to engage, and the wall of the well casing B.

The lower end" 21a of the non-metallic rubber-like packing sleeve is disposed within a lower expander member 22a, which may be identical to the upper expander member 22, although facing in an opposite direction. This lower expander member 22a has an expander surface 25a inclined in an upward and outward direction, engaging a companion internal expander surface 270 on an expansible flow preventing ring 26a which may be in the form of a helical spring like the other flow preventing member 26, although facing in an opposite direction. The lower end of the helical spring or expansible gage ring 26a engages a fixed lower gage ring 30 threadedly secured onto the upper end of a thrust-tube or sleeve 31, the lowerend of which is threadedly attached to a guide member 38 secured to the body of the tool. The lower expansible gage ring 260: normally occupies a retracted position with its periphery disposed no further outwardly than the periphery of the lower fixed gage ring 30. The lower ring 26a is also adapted to be expanded outwardly into engagement with the well casing B, to bridge the annular clearance space 19a between the lower gage ring and the casing wall.

Downward movement of the sleeve 31 and the lower "gage ring 30 with respect to the compression or booster sleeve 17 is limited by engagement of an inwardly directed flange 32 of the lower gage ring with an outwardly directed shoulder 33 provided on the lower portion of the compression sleeve 17.

To prevent leakage of fluid through the working clearance spaces between the body 10, on the one hand, and the compression sleeve 17 and expander 13, on the other hand, the expander may be prowded with an internal groove .34 receiving a non-metallic seal ring 35, such as a rubber or rubber-like O-ring, which is in slidable sealing engagement with the periphery of the body.

' As described in the above-identified patent application, the apparatus A disclosed is lowered in the well casing B to the location at which it is to be anchored in packed-off conditiontherewithin. When this position is reached, the slips 11 are prevented from moving upwardly by suitable means (not shown) which form no part of the present invention, but are specifically disclosed and described in the above-identified patent application, whereupon the body 10 is moved upwardly by the tubing string (not shown), the upward movement being transmitted through the guide member 38, thrust-sleeve 31 and lower gage ring 30 to the lower expansible gage ring 26a, which tends to remain in its retracted position, since a substantial force is required before it can be expanded outwardlyagainst the wall of the well casing. The lower expandible gage ring 26a transmits the longitudinal force of the body 10 to the lower expander member 22a, from where the force is transmitted through the packing sleeve 20, which has a proper hardness, to the upper expander member 22, from where it passes through the upper expandible gage Iring 26.to the upper abutment structure and expander 18, 13, carrying the expander upwardly with respect to the slips 11. The expander 13 is moved within the slips 11 to wedge the latter outwardly into firm anchoring engagement with the wall of the well casing B.

Following the anchoring of the slips against the well casing, the expander is prevented by the slips from moving upwardly to any further extent. Accordingly, a continuation of the upward movement and force of the body 10 of the tool will then shift the lower gage ring 30, expansible gage ring 26a, and lower expander member 22a, which together may be considered as constituting a lower abutment structure, toward the upper abutment structure, consisting of the upper expander member 22,

' upper expansible gage ring 26 and upper fixed abutment and gage structure 13a, 18. The movement of the lower abutment device toward the upper abutment device foreshortens and compresses the packing sleeve 20 in a longitudinal direction, causing it to expand outwardly into sealing engagement with the wall of the well casing B.

The upper and lower expansible gage rings 26, 26a have a very great resistance to outward expansion. As an example, a longitudinal force thereon of the order of about ten thousand to twenty five thousand pounds is required to expand them outwardly into engagement with the wall of the well casing. Accordingly, expansion of the packing sleeve 20 into full sealing engagement with the wall of the well casing occurs before there is any substantial expansion of the expandible gage rings 26, 26a in an outward direction. However, the expansible gage rings will be expanded outwardly against the well casing before a sufficient pressure or force is applied upon the packing sleeve as to cause it to extrude to any substantial extent into the clearance space 19 or 19a between the expander member 13, 18 or abutment 30 and the wall of the well casing.

As the upward expansible force on the body 10 in creases, the expander members 22, 22a begin expanding the expansible flow preventing rings 26, 26a in an outward direction. An increase in the upward force will cause the expanded packing sleeve 20 to slide upwardly along the wall of the well casing B, moving the upper expander member 22 towards the upper abutment or expander 13, 13a. When moving towards the latter, the expander member 22 will shift the upper expandible gage ring 26 outwardly toward the well casing. To place a definite limit on the extent of the expansion of the ring 26 against the wall of the well casing, the upper end of the upper expander member 22 will engage the upper abutment 1312, as shown in Fig. 2. At this time, several turns of the helical member 26 will be in engagement with the wall of the well casing B. The member 26 is also in contact with the expander surface 25 on the expander member 22, the upper end of the expansible ring engaging the upper abutment 1.3a or its gage ring 18. When this occurs, the annular space 19 between the upper expander member 13, 18 and the wall of the well casing is completely bridged by the expandible member 26, the rubber packing material being capable of flowing only partially around the upper expander member 22 until it contacts the expansible ring. The expansible ring 26 bridges this space, and also effectively bridges the annular space 19 around the fixed gage ring 18 and the wall of the well casing.

The lower expansible member 26a functions in a similar manner. As the upward force imposed thereon by the body 10 increases sufliciently, the lower gage ring 30 moves toward the lower expander member 22a, shifting the expansible ring 26a along the tapered surface 25a of thelatter and radially outward toward engagement with the wall of the well casing B, to bridge the annular clearance space between the lower expander member 22a and the casing wall. Although the force required to fully expand the lower expandible member 26a outwardly is rather high, yet such force is lower than the force imposed on the packing sleeve 20 which will cause it to tend to extrude through the clearance space between the lower expander member 22a and the casing wall. When such extruding forces are reached, as a result of further compression forces being exerted on the packing structure,

the expandible gage rings are both engaged firmly with pander 13 within slips 11, to hold the latter anchored against the well casing. Theupwardly directed forces imposed on the packing structure cannot extrude the packing sleeve 20 through any clearance spaces, in view of the bridging action of the upper expanding gage ring 26. The bridge formed is circumferentially continuous, there being no gaps at any point around its circumference through which the packing material can be forced.

Similarly, in the event that a very high pressure diflerential exists in the annulus above the packing structure 16 between the body of the tool and the well casing B, such downwardly directed force will merely slide the packing structure 16 downwardly, while it remains in a packed-off condition, as described in the above-identified patent application and in United States Patent 2,675,876. If the pressure differential in the annulus above the packing structure 16 is not too high, then the expandible gage rings 26, 26a may actually retract, at least to some extent, which will facilitate the sliding action of the packing structure 16 along the wall of the well casing when moving in a downward direction. However, in the event that the pressure becomes very high, then such great downwardly directed forces will expand the lower gage ring 26a into full contact with the wall of the well casing, preventing the pressure from extruding the packing material through the lower clearance spaces around the lower expander member 22a and around the fixed lower gage ring 30.

Regardless of the direction in which the pressure is acting upon the packing structure 16, when it is desired to release the tool and move it longitudinally Within the well casing, it is only necessary to relieve the pressure differential on the packing structure and lower the body 10. Such lowering action will move the lower fixed gage ring 30 away from the upper fixed gage structure 18, 13, permitting the expansible gage rings 26, 26a and the packing sleeve 20 to retract to their normal positions, such as disclosed in Fig. 1, wherein substantial clearance exists around the entire packing structure 16. The well tool A may be now moved longitudinally in the well casing to a new setting location, or withdrawn entirely from the well bore.

It is, accordingly, apparent that a packing structure has been provided which embodies expansible elements for insuring against the cold flowing of the packing material through any clearance spaces existing between parts of the apparatus and the wall of the surrounding enclosure, such as the wall of the well casing. The devices for preventing cold fiowing of the packing material are retractible, so that the release of the expansible force on the non-metallic, elastic packing member causes such devices 26, 26a to retract, which permits the apparatus to be moved, with facility, longitudinally in the well casing. Not only are the cold flow preventing devices expansible and retractable, but when expanded outwardly against the wall of the confining enclosure, to bridge the annular clearing spaces, no gaps remain longitudinally therethrough, into and through which the packing material can be forced. Because of the fact that the bridge members or gauge rings 26, 26a are flexible, they will conform to diflerent internal diameters of casings against which they engage, assuring that no gap remains through which the packing material will extrude.

The inventor claims:

1. In a packing assembly: a pliant packing engageable with a companion member; abutment means adjacent said packing and providing a clearance space with the companion member; an expander member engaging said packing and having a tapered surface; and a helical spring wound about an axis substantially coaxial of the packing; said spring engaging said abutment means and said tapered surface and shiftableby said tapered surface of said expander member laterally into engagement with the companion member to bridge said clearance space upon relative longitudinal movement between said expander member and abutment means while maintaining said spring in engagement with said expander member and abutment means.

2. In a packing assembly: a pliant packing engageable with a surrounding companion member; abutment means adjacent said packing and providing a clearance space with the companion member; an expander member engaging said packing and initially spaced from said abutment means, said expander member having a tapered external surface converging in a direction toward said abutment means; and an inherently co'ntractible helical spring wound about an axis substantially coaxial of said packing and engaging said abutment means and said expander member and expandible by said tapered surface of said expander member laterally outward into engagement with the companion member tobridge said clearance space upon movement of said expander member toward said abutment means while maintaining said spring in engagement with said expander member and abutment means.

3. In a packing assembly: a pliant packing engageable with a companion member; abutment means adjacent said packing and providing a clearance space with the companion member; a rigid metallic expander member engaging said packing and disposed between an end of said packing and said abutment means; and a shiftable expansible and contractible metallic one-piece flexible bridge member between and engaging said abutment means and said expander member and shiftable by said expander member laterally into engagement with the companion member to bridge said clearance space upon relative longitudinal movement between said expander member and abutment means while maintaining said bridge member in engagement with said expander member and abutment means; said bridge member having an arcuate extent of more than 360 degrees and having portions in overlapping contact when engaging the companion member, whereby there is an absence of any space extending longitudinally through said bridge member through which said packing can be forced.

4. In a packing assembly: a pliant packing engageable with a companion member; abutment means adjacent said packing and providing a clearance space with the companion member; a rigid metallic expander member engaging said packing and disposed between an end of said packing and said abutment means, said expander member having a tapered surface; a shiftable expansible and contractible metallic one-piece flexible bridge member between and engaging said abutment means and said tapered surface and shiftable by said tapered surface of said expander member laterally into engagement with the companion member to bridge said clearance space upon relative longitudinal movement between said expander member and abutment means while maintaining said bridge member in engagement with said expander member and abutment means, said expander member being engageable with said abutment means to limit the extent of lateral movement of said bridge member.

5. In a packing assembly: a pliant packing engageable with a surrounding companion member; abutment means adjacent said packing and providing a clearance space with the companion member; a rigid metallic expander member engaging said packing and initially spaced from said abutment means, said expander member being disposed between an end of said packing and said abutment means; an inherently contractible metallic one-piece flexible bridge member between and engaging said abutment means and said expander member and expandible by said expander member laterally outward into engagement with the companion member upon movement of said expander member toward said abutment means to bridge said clearance space while maintaining said bridge member in engagement with said expander member and abutment mine means;'said bridge member having an arcuate extent of more than 360 degrees and having portions in overlapping contact When engaging the companion member, whereby there is an absence of any space extending longitudinally through said bridge member through which said packing can be forced.

6. In a packing assembly: a pliant packing engageable with a surrounding companion member; abutment means adjacent said packing and providing a clearance space with the companion member; a rigid metallic expander member engaging said packing and initially spaced from said abutment means and disposed between an end of said packing and said abutment means, said expander member having an external tapered surface; an inherently contractible metallic one-piece flexible bridge member between and engaging said abutment means and said tapered surface and expandible by said tapered surface of said expander member laterally outward into engagement with the companion member upon movement of said expander member toward said abutment means to bridge said clearance space while maintaining said bridge member in engagement with said expander member and abutment means, said expander member being engageable with said abutment means to limit expansion of said bridge member.

7. In a packing assembly: a pliant packing engageable with a surrounding companion member; abutment means adjacent said packing and providing a clearance space with the companion member; a rigid metallic expander member engaging said packing and initially spaced from said abutment means and disposed between an end of said packing and said abutment means, said expander member having an external tapered surface converging in a direction toward said abutment means; an inherently contractible metallic one-piece flexible bridge member between and engaging said abutment means and said tapered surface and expandible by said tapered surface of said expander member laterally outward into engage- .ment with the companion member upon movement of said expander member toward said abutment means to bridge said clearance space while maintaining said bridge member in engagement with said expander member and abutmentmeans, said expander member being engageable with said abutment means to limit expansion of said bridge member.

8. .In a packing assembly: a pliant packing engageable with a companion member; abutment means adjacent said packing and providing a clearance space with the companion member; an expander memberengaging said packing and disposed between an end of said packing and said abutment means; and a helical spring wound about an axis generally coaxial of said packing member and disposed between and engaging said abutment means and said expander member; said expander member engaging a side portion of said spring and being movable relatively toward said abutment means and along said spring to shift said spring laterally into engagement with the companion member to bridge said clearance space while maintaining said spring in engagement with said expander member and abutment means.

9. In a packing assembly: a pliant packing engageable with a surrounding companion member; abutment means adjacent said packing and providing a clearance space with the companion member; an expander member engaging said packing and initially spaced from said abutment means and disposed between an end of said packing and said abutment means; a helical spring wound about an axis substantially coaxial of said packing and engaging and being disposed between said abutment means and said expander member; said expander member engaging an inner side portion of said spring and being movable relatively toward said abutment means and along said spring to shift said spring laterally outward into engagement with the companion member to bridge said clearance space While maintaining said spring in engagement with said expander member and abutment means.

References Cited in the file of this patent UNITED STATES PATENTS 785,907 McBride Mar. 28, 1905 1,357,958 Crowell Nov. 9, 1920 2,171,049 I Simmons Aug. 29, 1939 2,217,038 Alley Oct. 8, 1940 2,603,294 Barnes July 15, 1952 2,695,069 Baker et a1. Nov. 23, 1954 2,734,582 Bagnell Feb. 14, 1956 2,767,795 Bush Oct. 23, 1956 

